LED light fixture

Abstract

The invention relates to the field of lighting devices. An LED light fixture comprises: a housing which serves as a radiator for heat dissipation; at least one LED module in the form of a separate device comprising LEDs mounted on a separate board, the LED module being fastened to one side of the housing; and a power supply unit which is closed with a removable lid, the power supply unit being fastened to the other side of the housing. The housing is configured in the form of a thin-walled plate with a thickness of 2 mm or more, having a planar portion from which, along the length of two opposite sides of the planar portion, edge portions are bent away in the same direction to form side walls which are oppositely slanted at positive angles, the body of each side wall having openings with ends which extend into the planar portion. The power supply unit is mounted as a separate element which is fastened to the housing in an isolated manner on the rear side of the planar portion, at a distance from the planar portion. The invention makes it possible to increase the operational reliability of an LED light fixture by improving the dissipation of heat as a result of changing the shape of the heat-dissipating element of said light fixture.

Description

[0001] LED lamp

[0002] The present invention relates to the field of lighting devices and concerns the design of a LED luminaire intended for lighting highways, streets, road infrastructure, residential areas, industrial and park areas.

[0003] LED lighting is used to solve a wide range of problems, including outdoor road lighting and indoor lighting.

[0004] The invention is intended for installation on a pole, cable suspension, supporting structure or other similar overhead structure by hanging or securing to a bracket.

[0005] There are various types of mounting LED modules on heat sinks. While they offer undeniable convenience, they also have significant limitations due to the high heat output of LED modules, which significantly limits the power or size of the product and significantly impacts the pricing of the final product.

[0006] LEDs require strict adherence to temperature conditions during operation. This requirement stems from the fact that their efficiency and lifespan are significantly reduced by heating. The primary cause of LED heating is the heat generated during operation. Therefore, effective heat dissipation is essential for proper operation. Continuous operation at elevated temperatures significantly accelerates brightness reduction (degradation), ultimately leading to a shorter useful life. For example, experimental data for two identical LEDs operating at the same current showed that the LED lifespan will vary under different operating conditions: at an ambient temperature of -40°C, the crystal will warm up to no more than 25-30°C, while the LED lifespan can exceed 100,000 cycles.hours, and at a temperature of +40°C, on the contrary: the crystal will heat up to +75-90°C, accordingly, the estimated service life will decrease to 35,000 hours (a decrease in the brightness of the luminous flux by 30%).

[0007] The lifespan of an LED directly depends on the crystal's heating temperature; the lower the temperature, the longer the lifespan. The critical temperature for an organic silicon crystal is generally considered to be between 100-150°C. However, the rate of crystal degradation increases significantly as the current increases to the maximum permissible value, as well as with increasing temperature. Therefore, it is crucial to protect LEDs from overheating (see the article "Maximum LED Temperature" posted on the website: https: / / music4qood.ru / led-lamps-and-eauipment / maximum-temDerature-of-lecls-why-is-it-so-import...).

[0008] Phosphor degradation is primarily determined by temperature: the phosphor is typically applied directly to the crystal, which becomes quite hot. The maximum non-destructive operating temperature specified by LED developers typically does not exceed 110-150°C. However, such heating leads to phosphor degradation and, consequently, a change in the LED's color from pure white to violet or green.

[0009] This requires solving two problems: heat dissipation from the crystal through the LED's structural elements and heat dissipation from the LED luminaire's overall operation (reducing the overall heating of the luminaire's housing, which houses the LED). Typically, heat dissipation from the housing's interior is easily accomplished through ventilation holes, slots, heat sinks on the housing's surface, etc., but heat sink cooling remains an unresolved issue.

[0010] As an example, one can consider the design of a LED lamp, including a housing with a radiator fixed thereto, elements for fastening an LED matrix, protective glass and a holder with an opening and a mechanism for fastening a tubular support console, the housing of the lamp is made collapsible in the form of a base, in the windows of which in its central part at least one LED matrix is ​​mounted, a radiator is mounted on the base above the windows, longitudinal side walls are fixed on the sides of the base, connected by means of grooves and slots with air flow guides installed above the radiator and with at least two air flow guides of the holder, made in the form of ribs and mounted perpendicular to the longitudinal axis of the lamp, while the head part of the housing is made in the form of air flow guides mounted mainly parallel to the longitudinal axis of the lamp,and the lamp holder is made from a set of air flow guides, additionally connected to each other using at least three plates, the top of which is connected to at least two housing guides using grooves and slots (RLI 2506492, F21S 13 / 10, published 10.02.2014).,

[0011] The disadvantage of this solution is the technological complexity of producing a case with a heatsink. The case, made of a heat-conducting material, consists of a base on which a heatsink is mounted. The heatsink has a complex geometric shape with multiple thin-walled longitudinal fins. The LED components themselves and their power supply are mounted within the cavity of this case. It is traditionally believed that increasing the number of heatsink fins improves heat transfer from the case cavity to the outside environment. In reality, this does not fully address the heat dissipation issue. The heatsink is a complex element with a thickened base and thin, plate-like fins extending from it. Heat dissipation occurs through lateral bends, and increasing their number increases the amount of heat transferred to the outside environment.But in reality, heat from the LED light source is transferred to the heat-dissipating base, and from there through the heat-conducting material of the radiator fins to their heat-exchange surfaces, from where it is dissipated into the air.

[0012] However, just because the fins are cooled by airflow or convection doesn't mean the LEDs are cooled. Essentially, these luminaires employ a three-stage heat transfer process: in the first stage, heat warms the heat sink base, in the second stage, the base heats the fins, and in the third stage, the fins release the heat to the surrounding environment. This multistage heat transfer process for cooling the LED elements and power supply has proven satisfactory in practice for low-power LEDs. As the LED power increases, convective heat transfer at the fins becomes insufficient for this luminaire design, as it requires a significant increase in the heat sink area and the cross-section of the heat sink base, making the luminaire bulkier and heavier.In this case, when a bulky and heavy light fixture is placed on a city lighting bracket, a high windage is created, due to which we can observe the lights being torn off the brackets or displaced on the bracket by the wind.

[0013] A LED street light is known, comprising a radiator housing (made from a profile, cast, stamped or assembled from these parts) made of a heat-conducting material, with light module(s) installed therein, closed or unclosed lampshades, each of which has at least one solid-state light source and a current source(s) for powering them, the radiator housing-bracket has cooling slots, a central compartment and two peripheral compartments for accommodating light modules are made in the radiator housing, wherein the central compartment is intended to accommodate the power source(s) and the light module(s) or light module(s), and a heat-conducting material is used to reduce the thermal resistance between the external structures and the radiator housing of the light (RU 149502, F21S 4 / 00, published 10.01.2015).

[0014] This solution is adopted as a prototype.

[0015] The radiator case is unique in that it is thick-walled and features a base plate and side walls curved away from the base plate, ending in thin-walled cooling fins. The power supply is mounted in the cavity between the inclined walls, and the LED elements are located on the back of the base plate and on the inclined surfaces of the side walls.

[0016] This design doesn't guarantee cooling of the LED components and power supply. This is because the housing itself acts as a heat sink for the luminaire's operating components. The fins, however, remove heat from the housing. However, the housing heats up faster than the fins can remove heat. In a known solution, all housing surfaces, despite their unconventional tray-like shape for luminaires, are covered by the LED units mounted on them. In this case, the housing doesn't remove heat, but only absorbs it, heating up to the operating temperature of the LEDs (chips). The internal area between the sloping side walls (the bottom) is occupied by the power supply, which blocks heat transfer from both the side walls and the bottom. When heat is absorbed, the mass of the housing heats up, with a gradient from the surface of the outer wall to the interior of the material's structure. This heating of the housing occurs throughout its entire volume.At the fin-to-fin contact points, heat will be transferred to the fins, which will then convectively release it into the surrounding environment. This means that partial cooling will occur not on the LED components and power supply, but on the housing itself, and only in the areas where the fins meet. This solution also uses a similar cooling principle, which is only suitable for low-power LED light sources. As the power of these sources increases, a thermal regime will be created inside the housing that is equivalent to the overheating of the chips, significantly reducing the service life of the luminaire.

[0017] The present invention is aimed at achieving a technical result consisting of increasing the operational reliability of a LED lamp by improving heat dissipation due to a change in the shape of the heat-dissipating element of this lamp.

[0018] The said technical result is achieved in that in a LED luminaire comprising a housing made of a material with high thermal conductivity, which is a radiator for dissipating heat into the environment, a LED module fixed to one side of the housing in the form of a separate device containing LEDs mounted on a separate board, the back side of which is designed with the possibility of transferring heat into the environment, as well as a power supply unit fixed to the other side of the housing and closed by a removable cover (if any), the housing is made in the form of a platform of a rectangular or other shape in plan, from which, along two opposite sides, edge parts are bent along the length of the platform to one side to form side walls, inclined in opposite directions and in the body of which technological openings are made, and the power supply unit is mounted on a separate plate, which is insulatedly fixed to the housing and at a distance from the platform.

[0019] The specified features are essential and are interconnected with the formation of a stable set of essential features sufficient to obtain the required technical result.

[0020] The present invention is explained by a specific example of implementation, which, however, is not the only possible one, but clearly demonstrates the possibility of achieving the required technical result.

[0021] Fig. 1 - view of the assembled lamp from the side of the LED modules, view of the lamp from below;

[0022] Fig. 2 - side view of the assembled lamp according to Fig. 1;

[0023] Fig. 3 - end view of the assembled lamp according to Fig. 1;

[0024] Fig. 4 - top view of the lamp;

[0025] Fig. 5 - fragment of the lamp housing structure;

[0026] Fig. 6 shows the upward heat flows removed from the luminaire and released into the surrounding environment. The present invention considers a design for an LED luminaire that, by modifying the housing design, provides improved heat dissipation. This design allows, while maintaining the same dimensions and weight, to use more powerful LED modules that produce a higher luminous flux and a smaller heat dissipation area, including at elevated ambient temperatures. The improved heat dissipation system contributes to an increased service life for the equipment, due to the precisely calculated airflow generated by the difference in thermal pressure on the luminaire housing, which ensures the necessary cooling of the LED module and the power supply. The power supply itself is mounted on the housing using fasteners, due to which the power supply is not adjacent to the surface and is located at a distance of at least 5 mm.from the body, which creates an additional air flow and improves convection efficiency.

[0027] In general, the claimed LED luminaire (Figs. 1-4) comprises, as a base element, a housing 1 made of a material with high thermal conductivity, which also serves as a heat sink for dissipating heat into the surrounding environment. At least one LED module 2 is mounted on one side of the housing 1, in the form of a separate device containing LEDs 3 mounted on a separate circuit board 4, the back of which is designed to transfer heat to the surrounding environment.

[0028] On the other side of housing 1 is a power supply unit 5, which is covered by cover 6. In this design, the LED luminaire follows the typical circuit designs widely used in this field today. In such luminaires, heat is dissipated from the power supply unit via the heated walls of the power supply unit housing and directly through openings in the cover to the surrounding environment.

[0029] Heat is removed from the LED modules by heating the housing and heat is removed from the housing through heat-dissipating elements.

[0030] In the claimed invention, one of the main components of the LED lamp is a housing 1 in the form of a platform (Fig. 5), which functions as a radiator, onto which LED modules 2 and a base 7 with a power supply 5 are mounted. The platform is made of an aluminum alloy using cold stamping technology of sheet metal.

[0031] The platform is made in the form of a thin-walled plate (Fig. 5) with a platform 8 of a rectangular or other shape in plan, from which edge parts are bent along the length of the platform to one side under two oppositely lying sides to form side walls 9, inclined in opposite directions and in the body of which slots 10 are made, the end sections 11 of which from the side of the platform are made in this platform.

[0032] The shape and configuration, as well as the width of the slots 10 (Fig. 5) are specified in the process of heat transfer calculations and are not significant for the object under consideration within the framework of this application.

[0033] The presence of these holes is essential, as they allow for additional air flow to improve radiator cooling.

[0034] The plate has smooth surfaces. Thin-walled platform designations mean that the plate's thickness is significantly smaller than its other dimensions. Specifically, in the actual sample, the plate thickness for two LED modules is approximately 3 mm, with a platform length of 426 mm and a total platform width of 166 mm (with the height of the inclined walls being 44 mm). Other LED luminaire designs may also be available with regard to platform thickness, length, and width.

[0035] As the number of LED modules increases, the length or width of the platform increases.

[0036] This plate exhibits excellent resistance to bending and torsion, as the inclined walls, set apart at an angle greater than a right angle, act as stiffening ribs. On these walls, the vector of forces causing deformation does not coincide with the vector of forces deforming the platform. This explains the platform's relatively high load-bearing capacity and its resistance to shape changes.

[0037] Making slots 11 in the side walls with a bend of the slots towards the body of the platform allows for an increase in the heat removal area and improvement in the conditions of air flow around the environment, which accelerates the cooling process of the plate not only on the side walls, but also on the platform.

[0038] In Fig. 5, the area where the LED module's printed circuit board is adjacent is highlighted with a frame.

[0039] Fig. 6 shows the heat flow distribution emanating from the plate. It is evident that the heat sink, convecting upward, is significantly larger than the heat-generating zone on the LED module side. This indicates effective heat dissipation. Additional holes can be made on the surface of the pad to accelerate the plate cooling process. The holes on the surface of the product are optimally spaced and in the required number, enabling proper heat dissipation technology.

[0040] This design reduces the overall weight of the product while increasing the amount of heat removed from the light sources, which in turn allows the use of more powerful power sources without compromising quality or losing efficiency.

[0041] The new thin-walled plate design eliminates hot spots. When heated, the entire material structure of the thin-walled plate reaches a uniform temperature, and heat transfer occurs at a similar rate and is virtually uniform across the entire platform. Essentially, the entire platform is a surface with high thermal conductivity and heat transfer. This surface is also well irrigated by ambient air from all sides, thus cooling quickly. The design eliminates elements with high thermal resistance.

[0042] The design of the housing is based on a metal-hybrid thermal interface, which utilizes a new heat transfer mechanism. Directly contacting the surface of the heat source, this frame transfers heat directly and virtually losslessly. Since the thermal conductivity of aluminum is, on average, 100 times higher than that of thermal pastes, heat transfer by the metal frame becomes the dominant mechanism (see "Metal-Hybrid Thermal Interfaces with High Thermal Conductivity" by V. S. Kondratenko, Yu. I. Sakunenko, and A. A. Vysokanov, Applied Physics, 2017, No. 1, pp. 85-88). It has been proven that this design eliminates the presence of central layers in the structure with a temperature different from the surface layers. Both developed surfaces of the plate act as both heat sinks and heat transfer agents to the surrounding environment.However, the cooling time, in terms of temperature reduction rate, exceeds the rate of heating increase, which is confirmed by research into heat dissipation from LED circuit boards using thin-sheet metal elements (article "Local Heat Dissipation Based on Metallized Through Holes" by N.P. Poruchikov, All-Russian Scientific and Technical Student Conference "Student Scientific Spring 2016", posted online at: http: / / studvesna.ru). According to the data obtained, as stated in this article, as the heat-dissipating surface area of ​​the thin-sheet element increases, the time it takes to cool it to the desired temperature decreases.

[0043] LED modules 2 are placed on the side of the platform (Fig. 3) opposite the inclined walls, and the backs of the circuit boards are pressed tightly against the surface of the platform. The back surface of the board can be coated with a thermally conductive material or layer that improves heat transfer from the printed circuit board to the platform during contact pressure.

[0044] Power supply 5 is mounted on a separate, insulated housing 7, located on the back of the platform and at a distance from the platform. The housing rests on feet 12.

[0045] Cover 6, for example, is made of stainless steel and protects the electronic components inside from external impacts from foreign objects. Stainless steel is scratch-resistant. If necessary, the design allows access to the power supply without complete disassembly, requiring only a few steps, as the cover is removable. The cover can also be made of aluminum or other materials.

[0046] Thus, the unit, consisting of a separate plate, a power supply on this plate and a cover covering the power supply, is isolated from the case and does not participate in heating the case.

[0047] For reliable installation of the luminaire, there are various options for spatial attachment to surfaces:

[0048] - console mount (Fig. 1, 2 and 4, where the mounting unit 13 of the lamp on the console is attached to the platform);

[0049] - hanging mount using a swivel bracket with a 180° rotation angle;

[0050] - suspension mount using chains (this option is quick-release and increases the speed of installation / dismantling).

[0051] These allow you to attach the lamp to different surfaces, under different conditions, at any required angle to the required surface.

[0052] The claimed invention utilizes LEDs from OSRAM or other manufacturers, ensuring reliable operation throughout the warranty period. The LEDs, compactly placed on the board, allow for a reduced footprint without the risk of overheating. The modules are manufactured on an aluminum base (plate), allowing for more efficient and distributed heat dissipation upon contact with the platform surface.

[0053] Secondary optics, made of a translucent polymer, including polycarbonate, polymethyl methacrylate, or polyethylene, are installed on the platform with a polymer seal or a protective layer of another polymer mixture. This ensures IP67 protection, guaranteeing protection of the contacts from moisture and dust. This level of protection is also ensured by a sealing ring pressed into place along with the hardware where the wires connect to the LED modules and the heat-shrink tubing, ensuring protection from all sides.

[0054] The design of this product is developed and optimized for assembly line production, which improves product quality while minimizing defects and flaws compared to similar production methods. Assembly is performed using a specially developed technology and does not require highly qualified personnel, reducing production costs without compromising quality or efficiency.

[0055] The conducted research and testing demonstrated the real possibility of increasing the thermal energy output from the LED modules by changing the circuit design, shape, and design of the heatsink housing. This allowed the use of more powerful LEDs and increased the operating time of the luminaire.

[0056] Comparison Table 1 clearly demonstrates the advantages of the new heat dissipation scheme in combination with the design, which truly allows the use of more powerful power sources and LED modules with smaller luminaire dimensions, which in turn increases its efficiency.

[0057] Comparison Table 2 clearly demonstrates that the new luminaire design with an improved heat dissipation system truly allows for the use of powerful power sources and LED modules with smaller dimensions, lower weight, and a longer warranty period, which increases the benefits and quality of the luminaire for the end user throughout its entire service life. Table 1. Comparison of the characteristics of the medium-power luminaire according to the invention with the closest medium-power analog (DVO outdoor DKU-120 W).

[0058]

[0059] Table No. 2. Comparison of the characteristics of the luminaire according to the invention with the closest high-power analogue ("MODULE PRO" SVT-STR-MPRO- 79W-45X140-DUO-C)

[0060] " "

[0061]

Claims

CLAUSES OF THE INVENTION An LED luminaire comprising a housing made of a material with high thermal conductivity, which is a radiator for dissipating heat into the environment, at least one LED module fixed to one side of the housing in the form of a separate device containing LEDs mounted on a separate board, the back side of which is designed with the possibility of transferring heat into the environment, as well as a power supply unit fixed to the other side of the housing and closed with a removable cover, characterized in that the housing is made in the form of a thin-walled plate with a thickness of 2 mm with a platform, from which, on two opposite sides, edge parts are bent along the length of the platform to one side to form side walls, inclined in opposite directions with positive angles and in the body of which openings are made, the end sections of which on the side of the platform are made in this platform, and the power supply unit is mounted as a separate element,which is insulatedly mounted on the body on the back side of the platform and at a distance from the platform.

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